Tagged Questions

A cipher which uses a different encryption key every time, as long as the message. The key is XOR'ed with the message to render the cipher text which can then be XOR'ed with the same key to get the plain text.

Recently I've been delving into security algorithms, I already knew some of the (easy) math behind AES and RSA and how to and not to implement it. But well, i got a bit bored so i thought I'd just do ...

We know that the one-time pad is provably secure as a cipher to encrypt some data. Is there an algorithm which does the same just as a hash function? Can we get a provably secure hash function? Maybe ...

I understand that by definition one-time-pad keys cannot be reused but I was thinking about the case where it is used to send random data and couldn't find anything on the subject so here is my idea:
...

One of the main rules of the OTP is, that a key should never ever be reused.
But if we use some commutative operation (XOR for example) for generating the cipher text, then I don't see any difference ...

I was playing with the Vernam cipher on some online converter.
But when I tried to encrypt my message string with numbers, it remained unchanged.
Moreover, it was ignoring numbers and was encrypting ...

Suppose a $1000$-bit key used in the one-time pad is not randomly and uniformly generated.
Suppose that the values of the first $5$ bits are $0$, and the other $995$ bits are randomly generated and ...

i wondered what the security implications are if I do the following. If I had a large file encrypted with a OTP and want to change only a few bytes in the plaintext. what security vulnerabilities do I ...

I'm supposed to prove that OTP without the zero key $k=0^n$ is not perfectly secret anymore. I understand that it's not because an attacker learns something by looking at the plaintext and ciphertext. ...

One-Time-Pad is information theoretically secure as long as the random number stream is evenly long or longer than the data stream it encrypts, for a "decyphered" message could have been any message ...

Alice has a message, generates a one time pad, encrypts her message and sends it to Bob. Bob generates his own one time pad, encrypts the message again, and sends it back to Alice. Alice then decrypts ...

Assumptions:
Alice and Bob use (cryptographically secure, hardware-rng generated) 4096 bit keys.
Each message is encrypted using a new key; meaning: once a key is used, it's destroyed.
Alice and Bob ...

I have seen from time to time questions about various OTP schemes and "OTP" (i.e. stream cipher) schemes. The most common OTP troubles appear to be:
How to extend size of previously generated key or ...

Consider the One-Time Pad (OTP). Suppose two parties, A and B, generate a completely random secret key in a real-life meeting, and they keep this secret. Now A wants to send some message to B using ...

The main problem with OTP's is the fact that they can only be used once.
Would it be possible to use a random number that's, say, 512 digits, then use 256 of those for the (non-random) message, the ...

First off, I'm extremely sorry if this comes off as a "homework dump", but to clarify, it isn't. I don't want the answer, I want to know how to get to the answer. My cryptography professor gave us an ...

I have a Raspberry Pi single-board computer that happened to have an hardware true random number generator, based on some quantum effects on the processor silicon, baked into its BCM2835 chip and I ...

I've stumbled (jobwise) over a system where small messages (512 Bytes or less) are encrypted and decrypted using a simple XOR using a OTP. That OTP is created using a seed based on the individual user ...